IVF timing tweaked: could waiting 1-2 days boost baby chances?
NCT ID NCT04163133
First seen Jun 27, 2026 · Last updated Jun 27, 2026
Summary
This study compares the usual timing of the 'trigger' shot in IVF with a 1-2 day delay. Researchers want to see if waiting longer leads to more high-quality embryos and higher live birth rates. About 834 women undergoing their first or second IVF cycle will take part.
What this could mean
Our plain-language read of the trial. This is informational only, not medical advice or a prediction.
- What this could lead to
- If delaying the trigger improves outcomes, it could help couples undergoing IVF get more high-quality embryos and higher live birth rates.
- What could go wrong
- This is an early-stage study comparing two timing strategies, not a new drug or treatment. The benefit of a delay is unproven, and individual results may vary.
This is an AI summary of the original study and may miss details. Read our disclaimer.
Study facts
What this study's own registry entry says, in plain language.
- Phase
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Not a phased trial
Phase numbers describe drug development. The registry uses this when they do not apply, as it does for trials of devices, procedures or behaviour changes, and for observational studies.
- Participants
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About 834 people
The number the study aims to enrol. It can still change while the study runs.
- Started
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Apr 2020
- Expected to finish
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Mar 2028
An estimate. End dates often move.
- Lead sponsor
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Other sponsor
The registry's catch-all category, for sponsors it does not file as a company, a government agency, or a research network.
Who can take part
This study's own entry requirements. Only the study team can say for certain whether you qualify.
- Ages
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18 to 42 years
- Sex
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Female participants only
- Healthy volunteers
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Not accepted
This study is not open to healthy volunteers. The entry requirements below say who it is open to.
Show the full entry requirements Hide the full entry requirements
Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.
Inclusion Criteria: * Age: ≥18 and \<42 years old * AFC: ≥5 and \<20 * AMH: ≥1.1 ng/mL and \<2.5 ng/mL * BMI: ≥18.5 Kg/m2 and \<29 Kg/m * First or second ART cycle * Regular menstrual cycles (between 22 and 35 days) * Two ovaries present * Planned for single or double day 3 transfer * Infertile couples scheduled for their first IVF/ICSI cycle with fixed antagonist protocol. * Informed consent obtained. Exclusion Criteria: * Women with contraindication for IVF or ICSI, such as poorly controlled type 1 or type 2 diabetes mellitus; undiagnosed liver disease or dysfunction (based on serum liver enzyme test results); renal disease or abnormal serum renal function; significant anemia; history of deep venous thrombosis, pulmonary embolus or cerebrovascular accident; uncontrolled hypertension or known symptomatic heart disease; history of (or suspected) cervical carcinoma, endometrial carcinoma or breast carcinoma; and undiagnosed vaginal bleeding. * Previous history of poor ovarian response (\<4 oocytes retrieved) with a maximal dose of OS (≥300 IU/day) or OHSS, regardless of gonadotropin dose * Known reasons for impaired implantation (i.e. hydrosalpinx, fibroid distorting the endometrial cavity, Asherman's syndrome, thrombophilia or endometrial tuberculosis) * Repeated miscarriages (\>2 previous biochemical pregnancies or \>2 spontaneous miscarriages) * Recurrent implantation failure (\>3 failed cycles with good quality embryos) * PCOS * Untreated thyroid disfunction * Administration of exogenous E2, P4 or gonadotropins in the preceding menstrual cycle * Active female smoking * Ongoing pregnancy * Women who have previously enrolled in the trial * Those unable to comprehend the investigational nature of the proposed study * either male partner or female partner has to receive donor sperm or donor eggs. * Either male partner or female partner has to receive PGD and PGS.
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Conditions
The condition(s) this trial relates to.
As listed by the trial registrant
The condition terms exactly as the trial's registrant entered them.
How to take part
Only the study team decides who joins. These are the ways to reach them.
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The places running it
1 site. The list below names each one and where it is.
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The official record
ClinicalTrials.gov lists the study team's own contact details, including names and phone numbers. We don't republish those.
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A doctor treating you
A doctor who knows your case can contact a study site on your behalf, and can tell you whether this study is worth pursuing at all.
Contacts and locations
Locations
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Peking Univesity Third Hospital
RECRUITINGBeijing, Beijing Municipality, 100191, China
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- Sperm sorting showdown: can a microchip pick the best sperm for pregnancy?
- Could your genes predict when fertility fades?
- Can virtual reality goggles take the sting out of a fertility procedure?